Zirconia-stabilized multi-filamentary niobium-tin superconducting wire

ABSTRACT

A multi-filament superconducting wire in which the filaments comprise zirconia-stabilized ultra-fine grain Nb 3 Sn. The superconducting wire is formed by wire-drawing a preform comprising a metallic matrix and at least one niobium alloy rod having zirconium and oxygen in solid solution and heat treating the drawn wire in the presence of tin to yield at least one continuous filament comprising ultra-fine grain Nb 3 Sn having semi-coherent ZrO 2  precipitates disposed therein. The ZrO 2  precipitates serve to stabilize the ultra-fine grain microstructure of the Nb 3 Sn at temperatures up to 1100° C. and allows Nb 3 Sn to maintain the ultra-fine grain microstructure when heat treated at temperatures that are greater than those previously used. By using higher temperatures to form Nb 3 Sn, the time required for heat treatment can be significantly reduced.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application is a DIVISION of U.S. patent application Ser. No.10/248,339, filed Jan. 10, 2003 now abandoned.

BACKGROUND OF INVENTION

The invention is related to superconducting wire having at least onefilament of superconducting material. More particularly, the inventionrelates to a multi-filament superconducting wire comprising azirconia-stabilized, niobium tin superconductor and a matrix material,and a method of making such a multi-filament superconducting wire.

Superconducting wires comprising multiple filaments of niobium-basedsuperconductors, such as niobium tin (hereinafter referred to as“Nb₃Sn”), are used in a variety of electromagnetic applications, such asmagnets, motors, and transformers. To maintain sufficient criticalcurrent density in the superconducting wire during operation atcryogenic temperatures of less than 17.5 K, the Nb₃Sn comprisingfilaments within the wire must have an ultra-fine grain size of lessthan about 1 micron. One of the processes that is used to manufacturemulti-filament Nb₃Sn wire is the “bronze process,” in which ultra-finegrains of Nb₃Sn are formed on the surface of wire-drawn niobiumfilaments by heat treatment for several days at relatively lowtemperatures.

The length of the heat treatment required to produce ultra-fine grainNb₃Sn is exceedingly time-intensive and uneconomical. Therefore, what isneeded is a superconducting wire comprising ultra-fine grain Nb₃Sn thatis formed by a more rapid process. What is also needed is a method ofmore rapidly making a multi-filament superconducting wire comprisingultra-fine grained Nb₃Sn.

SUMMARY OF INVENTION

The present invention meets these and other needs by providing amulti-filament superconducting wire in which the filaments comprisezirconia-stabilized ultra-fine grained (also referred to hereinafter as“UFG”) Nb₃Sn. The superconducting wire is formed by deformationprocessing of a preform comprising a metallic matrix and at least oneniobium alloy rod having precipitates of zirconia, also known aszirconium oxide and hereinafter referred to as “ZrO₂.” The ZrO₂precipitates serve to stabilize the ultra-fine grained microstructure ofthe Nb₃Sn at temperatures up to 1100° C. and allows Nb₃Sn to maintainthe ultra-fine grained microstructure when heat treated at temperaturesthat are greater than those previously used. By using highertemperatures to form Nb₃Sn, the time required for heat treatment can besignificantly reduced.

Accordingly, one aspect of the invention is to provide a superconductingwire. The superconducting wire comprises: at least one filament having afilament diameter, wherein the at least one filament is continuous andcomprises a plurality of Nb₃Sn grains having a plurality of ZrO₂precipitates disposed therein, and wherein the plurality of Nb₃Sn grainshave an average grain size of less than about 10 percent of the filamentdiameter; and a metallic matrix surrounding and contacting the at leastone filament, wherein the metallic matrix is electrically conductive attemperatures below about 77 K and has a coefficient of thermal expansionthat is substantially the same as or greater than that of Nb₃Sn.

A second aspect of the invention is to provide a preform for forming asuperconducting wire comprising at least one filament having a filamentdiameter, wherein the at least one filament comprises a plurality ofNb₃Sn grains having a plurality of ZrO₂ precipitates disposed thereinand a metallic matrix surrounding and contacting the at least onefilament. The preform comprises: at least one niobium alloy rodcomprising a niobium alloy having oxygen and zirconium in solidsolution, wherein zirconium and oxygen are present in an atomic ratio ofabout 1:2; and a metallic preform matrix surrounding and contacting theat least one niobium alloy rod, wherein the metallic preform matrixcomprises tin.

A third aspect of the invention is to provide a superconducting wire,formed from a preform comprising at least one niobium alloy rodcomprising a niobium alloy having oxygen and zirconium in solidsolution, wherein zirconium and oxygen are present in an atomic ratio ofabout 1:2, and a metallic preform matrix surrounding and contacting theat least one niobium alloy rod, wherein the metallic preform matrixcomprises tin. The superconducting wire comprises: a plurality offilaments, wherein each of the plurality of filaments is continuous andhas a filament diameter, wherein at least one filament comprises aplurality of Nb₃Sn grains having a plurality of ZrO₂ precipitatesdisposed therein, and wherein the plurality of Nb₃Sn grains has anaverage grain size of less than about 10 percent of the filamentdiameter; and a metallic matrix surrounding and contacting the pluralityof filaments, wherein the metallic matrix is electrically conductive attemperatures below about 77 K and has a coefficient of thermal expansionthat is substantially the same as or greater than that of Nb₃Sn.

A fourth aspect of the invention is to provide an electromagnetic devicecomprising at least one superconducting wire, wherein thesuperconducting wire is formed from a preform comprising at least oneniobium alloy rod comprising a niobium alloy having oxygen and zirconiumin solid solution, wherein zirconium and oxygen are present in an atomicratio of about 1:2, and a metallic preform matrix surrounding andcontacting the at least one niobium alloy rod, and wherein the metallicpreform matrix comprises tin. The superconducting wire comprises: aplurality of filaments, wherein each of the plurality of filaments has afilament diameter, wherein at least one filament is continuous andcomprises a plurality of Nb₃Sn grains having a plurality of ZrO₂precipitates disposed therein, wherein the plurality of Nb₃Sn grains hasan average grain size of less than about 10 percent of the filamentdiameter; and a metallic matrix surrounding and contacting the pluralityof filaments, and wherein the metallic matrix is electrically conductiveat temperatures below about 77 K and has a coefficient of thermalexpansion that is substantially the same as or greater than that ofNb₃Sn.

A fifth aspect of the invention is to provide a method of making asuperconducting wire comprising at least one filament, wherein the atleast one filament is continuous and comprises a plurality of Nb₃Sngrains having a plurality of ZrO₂ precipitates disposed therein and ametallic matrix surrounding and contacting the at least one filament.The method comprises the steps of: providing a niobium alloy havingoxygen and zirconium in solid solution, wherein zirconium and oxygen arepresent in an atomic ratio of about 1:2; forming at least one niobiumalloy rod from the niobium alloy; providing a metallic matrix materialto the at least one niobium alloy rod; forming a wire from the metallicmatrix material and the at least one niobium alloy rod; and heattreating the wire at a predetermined temperature for a predeterminedtime, thereby forming the superconducting wire.

A sixth aspect of the invention is to provide a method of making apreform for a superconducting wire comprising at least one niobium alloyrod having oxygen and zirconium in solid solution, wherein zirconium andoxygen are present in an atomic ratio of about 1:2, and a metallicpreform matrix surrounding and contacting the at least one niobium alloyrod. The method comprises the steps of: providing a niobium alloy havingoxygen and zirconium in solid solution, wherein zirconium and oxygen arepresent in an atomic ratio of about 1:2; forming at least one niobiumalloy rod from the niobium alloy; providing a metallic matrix materialto the at least one niobium alloy rod; and forming a preform bysurrounding the at least one niobium alloy rod with the metallic matrixmaterial such that the metallic matrix material contacts the at leastone niobium alloy rod.

A seventh aspect of the invention is to provide a superconducting wirecomprising: at least one filament having a filament diameter, whereinthe at least one filament is continuous and comprises a plurality ofNb₃Sn grains having a plurality of ZrO₂ precipitates disposed therein,wherein the plurality of Nb₃Sn grains have an average grain size of lessthan about 10 percent of the filament diameter; and a metallic matrixsurrounding and contacting the at least one filament, wherein themetallic matrix has a coefficient of thermal expansion that issubstantially the same as or greater than that of Nb₃Sn, and wherein thesuperconducting wire is formed by: providing a niobium alloy havingoxygen and zirconium in solid solution, wherein zirconium and oxygen arepresent in an atomic ratio of about 1:2; forming at least one niobiumalloy rod from the niobium alloy; providing a metallic matrix materialto the at least one niobium alloy rod; forming a wire from the metallicmatrix material and the at least one niobium alloy rod; and heattreating the wire at a predetermined temperature for a predeterminedtime to form the superconducting wire.

These and other aspects, advantages, and salient features of the presentinvention will become apparent from the following detailed description,the accompanying drawings, and the appended claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic representation of a cross-sectional view of thesuperconducting wire of the present invention;

FIG. 2 is a schematic representation of side and cross-sectional viewsof a multi-wire cable formed from the superconducting wire of thepresent invention

FIG. 3 is a schematic representation of a cross-sectional view of aflattened tape formed from the superconducting wire of the presentinvention; and

FIG. 4 is a schematic representation of side and cross-sectional viewsof a laminated wire formed from the super-conducting wire of the presentinvention.

DETAILED DESCRIPTION

In the following description, like reference characters designate likeor corresponding parts throughout the several views shown in thefigures. It is also understood that terms such as “top,” “bottom,”“outward,” “inward,” and the like are words of convenience and are notto be construed as limiting terms.

Referring to the drawings in general and to FIG. 1 in particular, itwill be understood that the illustrations are for the purpose ofdescribing one embodiment of the invention and are not intended to limitthe invention thereto.

FIG. 1 is a schematic representation of a cross-sectional view of thesuperconducting wire 100 of the present invention. Superconducting wire100 includes at least one filament 110. Although seven such filaments110 are represented in FIG. 1, there is no limit to the number offilaments 100 contained within superconducting wire 100. Superconductingwire 100 may, for example, comprise a monofilament.

Filament 110 comprises a plurality of niobium-tin (hereinafter referredto as “Nb₃Sn”) grains that form continuous filament 110. A plurality ofzirconium oxide (hereinafter referred to as “ZrO₂”) precipitates arepresent within the plurality of Nb₃Sn grains. The ZrO₂ precipitatesserve to stabilize the ultra-fine grained microstructure of the Nb₃Sn attemperatures up to 1100° C. and inhibit Nb₃Sn grain growth, thusallowing Nb₃Sn to maintain the ultra-fine grained microstructure whenheat treated at temperatures that are greater than those previouslyused. At least one semi-coherent ZrO₂ precipitate is present in each ofthe plurality of Nb₃Sn grains to stabilize each Nb₃Sn grain and inhibitNb₃Sn grain growth.

Superconducting Nb₃Sn having ZrO₂ precipitates has been previouslydescribed in: U.S. Pat. No. 5,505,790, entitled “Method for EnhancingCritical Current in Triniobium Tin” by Mark G. Beuz, Howard R. Hart,Jr., Melissa L. Murray, Robert L. Zabala, Bruce A. Knudsen, and ThomasR. Raber, issued on Apr. 9, 1999; U.S. Pat. 5,522,945, entitled “Methodfor Forming Triniobium Tin Superconductor with Bismuth,” by Melissa L.Murray, Mark G. Benr, and Bruce A. Knudsen, issued on Jun. 4, 1996; U.S.Pat. No. 5,540,787, entitled “Method of Forming Triniobium TinSuperconductor.” by Neil A. Johnson, Melissa L. Murray, Thomas R. Raber,and Mark G. Benz, issued on Jul. 30, 1996; and U.S. Pat. No. 5,472,936,entitled “Method for Making Triniobium Tin Semiconductor,” by Mark G.Benz, Neil A. Johnson, Melissa L. Murray, Robert I. Zabala, Louis E.Hibbs, Jr., and Bruce A. Knudsen, issued on Dec. 5, 1995, which arcincorporated herein by reference in their entirety.

The plurality of Nb₃Sn grains are ultrafine grains (also referred tohereinafter as “UFG”) having an average grain size that is less thanabout 10 percent of the diameter of filament 110. The diameter offilament 110 is less than about 10 microns; thicker filaments tend tofracture more easily when wire 100 is bent or wound, as is common inapplications for which wire 100 is intended. In one embodiment, filament110 has a diameter of less than about 2 microns, and, preferably,between about 1 micron and about 2 microns. Likewise, larger Nb₃Sn grainsizes impede the ability of filament 110 to bend. The average grain sizeof the plurality of Nb₃Sn grains is less than about 1 micron, and,preferably, less than about 200 nanometers.

In one embodiment, wire 100 further includes at least one filament 110that comprises another superconducting material, such as, but notlimited to, elemental niobium, niobium zirconium alloy, and combinationsthereof.

The at least one filament 110 is surrounded by a metallic matrix 120,which surrounds and contacts the at least one filament 110. Metallicmatrix material 120 is electrically conductive at cryogenic temperatures(i.e., below about 77 K). In order to prevent breakage of wire 100during cycling between room temperature and cryogenic temperatures,metallic matrix has a coefficient of thermal expansion that iscompatible with that of the plurality of Nb₃Sn grains that form the atleast one filament 110. In the temperature range 4.2 K to 456 K, Nb₃Snhas a coefficient of thermal expansion (ΔL/L_(o)) of 0.282%. Whenmetallic matrix 120 has a coefficient of thermal expansion that issubstantially the same as that of Nb₃Sn, zero strain is imparted to theat least one filament 110. When metallic matrix 120 has a coefficient ofthermal expansion that is greater than that of Nb₃Sn, a compressivestress—which tends to increase the critical current of the at least onefilament 110 and superconducting wire 100—is imparted to the at leastone filament 110. If metallic matrix 120 has a coefficient of thermalexpansion that is less than that of Nb₃Sn, a tensile strain—which tendsto decrease the critical current of the at least one filament 110 andsuperconducting wire 100—is imparted to the at least one filament 110.Thus, metallic matrix 120 should have a coefficient of thermal expansionthat is substantially the same as or greater than that of Nb₃Sn.

Metallic matrix 120 is formed from a metallic preform matrix thatcomprises tin. In one embodiment, the metallic preform matrix is acopper-tin bronze. The metallic preform matrix preferably comprisesbetween about 5 atomic percent and about 13 atomic percent tin.

The superconducting wire 100 of the present invention is formed by firstproviding a niobium alloy comprising niobium, zirconium, and oxygen,wherein zirconium and oxygen are present in a ratio of about 1:2 (i.e.,Zr:O is approximately 1:2). In one embodiment of the invention, theniobium alloy is prepared by first melting, preferably by vacuum arcmelting, an alloy of elemental niobium and niobium oxide (hereinafterreferred to as “Nb₂O₅”) to decompose the Nb₂O₅ and produce an ingot ofelemental niobium in which between about 1 and about 3 atomic percentoxygen are dissolved. Zirconium is then provided to the niobium ingot. Asufficient amount of zirconium is provided such that zirconium andoxygen are present in a ratio of about 1:2. Zirconium may comprise up toabout 8 atomic percent of the niobium ingot. In one embodiment, anamount of zirconium that is sufficient to comprise about one atomicpercent of the niobium alloy is provided. The niobium ingot andzirconium are then melted, preferably by vacuum arc re-melting, to forma niobium alloy in which zirconium and oxygen are present in solidsolution in an atomic ratio of about 1:2 within the re-melted ingot. Inone embodiment, the re-melted niobium alloy ingot, which now containsoxygen and zirconium in solid solution, is heat treated at a temperaturebetween about 500° C. and about 900° C. to homogenize the re-meltedniobium alloy ingot.

The re-melted niobium alloy ingot, now containing a solid solution ofzirconium and oxygen, is next formed into at least one niobium alloyrod. The at least one niobium alloy rod may be formed by a variety ofprocesses. In one embodiment, the at least one niobium alloy rod iselectron discharge milled from the re-melted ingot. Alternatively, theat least one niobium alloy rod may be formed by other techniques, suchas, but not limited to, casting at least one niobium alloy rod from there-melted niobium alloy ingot, drawing at least one niobium alloy rodform the re-melted niobium alloy ingot, and extruding at east oneniobium alloy rod from the re-melted niobium alloy ingot. Once formed,the mechanical workability of the at least one niobium alloy rod may befurther increased by cold-working the at least one niobium alloy rod.Cold-working methods that may be used include, but are not limited to,swaging, extrusion, wire drawing, and the like.

A metallic matrix material is then provided to the at least one niobiumalloy rod such that the metallic matrix material surrounds and contactsthe at least one niobium alloy rod. In one embodiment, the metallicmatrix material is provided to the at least one niobium alloy rod toform a preform in which the metallic matrix material surrounds andcontacts the at least one niobium alloy rod. The metallic matrixmaterial comprises between about 5 weight percent and about 13 weightpercent tin. In one embodiment, the metallic matrix material is acopper-tin bronze. The preform may be formed by wrapping a sheet of themetallic matrix material around the at least one niobium alloy rod.Alternatively, the preform may be formed by providing the metallicmatrix material in a solid form through which holes are drilled and intowhich the at least one niobium alloy rod is inserted.

The metallic matrix material and the at least one niobium alloy rod arethen formed into a wire by first extruding the preform, followed byeither wire-drawing or swaging the extruded preform. Once drawn orswaged, the preform may be re-stacked by repeating the extrusion step,followed by the drawing or swaging steps, to achieve the desired wirediameter. The re-stacking step may be repeated as many times asnecessary until the desired wire diameter is obtained. The resultingwire comprises at least one filament surrounded by the metallic matrixmaterial, wherein the at least one filament comprises a niobium alloyhaving oxygen and zirconium in solid solution in an atomic ratio ofabout 1:2.

After the wire is formed, it is heat treated at a predeterminedtemperature for a predetermined time, to form a superconducting wire 100comprising filaments formed from a plurality of Nb₃Sn grains having aplurality of ZrO₂ precipitates. In one embodiment, the drawn or swagedwire is heat treated for up to 48 hours at a temperature of betweenabout 700° C. and about 1100° C. During the heat treatment, tin diffusesfrom the bronze metallic matrix material into the at least one filamentand reacts with the elemental niobium therein to form grains of Nb₃Sn inthe filament. The Nb₃Sn grains generally contain ZrO₂ precipitates.

In some instances, tin does not completely diffuse into the at least onefilament 110. Consequently, the at least one filament 110 may comprise areaction layer of Nb₃Sn grains surrounding a core comprising elementalniobium.

Because Nb₃Sn is a brittle material, the at least one filament 110 ofsuperconducting wire 100 may be subject to breakage when superconductingwire 100 is, for example, wound with other wires to form a cable orwound around a magnet or motor armature. This difficulty may be overcomeby winding the drawn or swaged wire prior to heat treatment.

Superconducting wire 100 may be formed into similar electricallyconducting structures, including, but not limited to, flattened tapes,laminated wires formed from multiple wires, and wound multi-wire cables.Schematic views of multi-wire cable 200, flattened tape 300, andlaminated wire 400 formed from superconducting wire 100 are shown inFIGS. 2, 3, and 4, respectively. Applications for superconducting wire100 are found in electromagnetic devices such as, but not limited to:superconducting magnets, such as that described in U.S. Pat. No.6,172,588, entitled “Apparatus and Method for a Superconductive Magnetwith Pole Piece,” by Evangelos Trifon Laskaris and Michael AnthonyPalmo, issued on Jan. 9, 2001, which is incorporated herein by referencein its entirety; motors; transformers; and generators. Suchelectromagnetic devices may in turn be incorporated into larger systems,such as, for example, a magnetic resonance imaging system.

While typical embodiments have been set forth for the purpose ofillustration, the foregoing description should not be deemed to be alimitation on the scope of the invention. Accordingly, variousmodifications, adaptations, and alternatives may occur to one skilled inthe art without departing from the spirit and scope of the presentinvention.

1. A method of making a superconducting wire, comprising the steps of:a) melting an alloy of elemental niobium and Nb₂O₅ to produce an ingotof elemental niobium having oxygen dissolved therein; b) meltingzirconium and the niobium ingot to form a niobium alloy, the niobiumalloy having zirconium and oxygen in solid solution, wherein zirconiumand oxygen are present in an atomic ratio of about 1:2; c) forming atleast one niobium alloy rod from the niobium alloy; d) providing ametallic matrix material to the at least one niobium alloy rod; e)forming a wire from the metallic matrix material and the at least oneniobium alloy rod, the metallic matrix material comprising between about5 weight percent and about 13 weight percent Sn; and f) heat treatingthe wire at a predetermined temperature for a predetermined time suchthat the wire comprises filaments formed from a plurality of Nb₃Sngrains having a plurality of ZrO₂ precipitates disposed therein, whereinthe plurality of Nb₃Sn grains have an average grain size of less thanabout 1 micron, thereby forming the superconducting wire.
 2. The methodaccording to claim 1, wherein the step of melting an alloy of elementalniobium and Nb₂O₅ to produce an ingot of elemental niobium having oxygendissolved therein comprises vacuum arc melting the alloy.
 3. The methodaccording to claim 1, wherein the step of melting zirconium and theniobium ingot to form a niobium alloy having zirconium and oxygen insolid solution comprises vacuum arc remelting the zirconium and theniobium ignot.
 4. The method according to claim 1, further including thestep of homogenizing the niobium alloy.
 5. The method according to claim4, wherein the step of homogenizing the niobium alloy comprises heattreating the niobium alloy at a predetermined temperature for apredetermined time.
 6. The method according to claim 1, wherein the stepof forming at least one niobium alloy rod from the niobium alloycomprises one of electron discharge milling the niobium alloy to form atleast one niobium alloy rod therefrom, casting at least one niobiumalloy rod from the niobium alloy, extruding at least one rod from theniobium alloy, and drawing at least one niobium alloy rod from theniobium alloy.
 7. The method according to claim 6, further including thestep of cold-working the at least one niobium alloy rod.
 8. The methodaccording to claim 7, wherein the step of cold-working the at least oneniobium alloy rod comprises at least one of swaging, extruding, andwire-drawing the at least one niobium alloy rod.
 9. The method accordingto claim 1, wherein the step of forming a wire from the metallic matrixmaterial and the at least one niobium alloy rod comprises: a) forming apreform by surrounding the at least one niobium alloy rod with themetallic matrix material such that the metallic matrix material contactsthe at least one niobium alloy rod; and b) forming a wire from thepreform.
 10. The method according to claim 9, wherein the step offorming a wire from the preform comprises extruding the wire followed byone of drawing the wire and swaging the wire.
 11. The method accordingto claim 10, further comprising the step of re-stacking the wirefollowing one of drawing the wire and swaging the wire, wherein the stepof re-stacking the wire comprises extruding the wire followed by one ofdrawing the wire and swaging the wire.
 12. The method according to claim11, wherein the step of re-stacking is repeated at least once.
 13. Themethod according to claim 1, wherein the step of heat treating the wireat a predetermined temperature for a predetermined time comprises heattreating the wire at a temperature of between about 700° C. and about1100° C. for a time of up to about 48 hours.
 14. The method according toclaim 1, wherein the step of heat treating the wire at a predeterminedtemperature for a predetermined time comprises winding the wire and heattreating the wire at a predetermined temperature for a predeterminedtime after winding the wire.
 15. A method of making a preform for asuperconducting wire, comprising the steps of: a) melting an alloy ofelemental niobium and Nb₂O₅ to produce an ingot of elemental niobiumhaving oxygen dissolved therein; b) melting zirconium and the niobiumingot to form a niobium alloy, the niobium alloy having zirconium andoxygen in solid solution wherein zirconium and oxygen are present in anatomic ratio of about 1:2; and c) forming at least one niobium alloy rodfrom the niobium alloy; d) forming a preform by surrounding the at leastone niobium alloy rod with a metallic matrix material comprising Sn suchthat the metallic matrix material contacts the at least one niobiumalloy rod.
 16. The method according to claim 15, wherein the step ofmelting an alloy of elemental niobium and Nb₂O₅ to produce an ingot ofelemental niobium having oxygen dissolved therein comprises vacuum arcmelting the alloy.
 17. The method according to claim 15, wherein thestep of melting zirconium and the niobium ingot to form a niobium alloyhaving zirconium and oxygen in solid solution comprises vacuum arcremelting the zirconium and the niobium ignot.
 18. The method accordingto claim 17, further including the step of homogenizing the niobiumalloy.
 19. The method according to claim 18, wherein the step ofhomogenizing the niobium alloy comprises heat treating the niobium alloyat a predetermined temperature for a predetermined time.
 20. The methodaccording to claim 15, wherein the step of forming at least one niobiumalloy rod from the niobium alloy comprises one of electron dischargemilling the niobium alloy to form at least one niobium alloy rodtherefrom, casting at least one niobium alloy rod from the niobiumalloy, extruding at least one rod from the niobium alloy, and drawing atleast one niobium alloy rod from the niobium alloy.
 21. The methodaccording to claim 15, further including the step of cold-working the atleast one niobium alloy rod.
 22. The method according to claim 21,wherein the step of cold-working the at least one niobium alloy rodcomprises at least one of swaging, extruding, and wire-drawing the atleast one niobium alloy rod.
 23. The method according to claim 15,further including the steps of: a) forming a wire from the metallicmatrix material and the at least one niobium alloy rod; and b) heattreating the wire at a predetermined temperature for a predeterminedtime such that the wire comprises filaments formed from a plurality ofNb₃Sn grains having a plurality of ZrO₂ precipitates disposed therein,wherein the plurality of Nb₃Sn grains have an average grain size of lessthan about 1 micron, thereby forming the superconducting wire.
 24. Themethod of claim 15, wherein an amount of Sn in the metallic matrixmaterial is between about 5 weight percent and about 13 weight percent.25. A method of making a superconducting wire, comprising the steps of:a) melting an alloy of elemental niobium and Nb₂O₅ to produce an ingotof elemental niobium having oxygen dissolved therein; b) meltingzirconium and the niobium ingot to form a niobium alloy, the niobiumalloy having zirconium and oxygen in solid solution, wherein zirconiumand oxygen are present in an atomic ratio of about 1:2; c) forming atleast one niobium alloy rod from the niobium alloy; d) forming a wirefrom a metallic matrix material and the at least one niobium alloy rod,the metallic matrix material comprising a mixture of Cu and Sn; and e)heat treating the wire at a predetermined temperature for apredetermined time such that the wire comprises filaments formed from aplurality of Nb₃Sn grains having a plurality of ZrO₂ precipitatesdisposed therein, wherein the plurality of Nb₃Sn grains have an averagegrain size of less than about 1 micron, thereby forming thesuperconducting wire.
 26. The method according to claim 25, furtherincluding the step of cold-working the at least one niobium alloy rod.27. The method according to claim 26, wherein the step of cold-workingthe at least one niobium alloy rod comprises at least one of swaging,extruding, and wire-drawing the at least one niobium alloy rod.
 28. Themethod according to claim 25, wherein the step of forming a wire fromthe metallic matrix material and the at least one niobium alloy rodcomprises: a) forming a preform by surrounding the at least one niobiumalloy rod with the metallic matrix material such that the metallicmatrix material contacts the at least one niobium alloy rod; and b)forming a wire from the preform.
 29. The method according to claim 28,wherein the step of forming a wire from the preform comprises extrudingthe wire followed by one of drawing the wire and swaging the wire. 30.The method according to claim 29, further comprising the step ofre-stacking the wire following one of drawing the wire and swaging thewire, wherein the step of re-stacking the wire comprises extruding thewire followed by one of drawing the wire and swaging the wire.
 31. Themethod according to claim 30, wherein the step of re-stacking isrepeated at least once.
 32. The method according to claim 25, whereinthe step of heat treating the wire at a predetermined temperature for apredetermined time comprises heat treating the wire at a temperature ofbetween about 700° C. and about 1100° C. for a time of up to about 48hours.
 33. The method according to claim 25, wherein the step of heattreating the wire at a predetermined temperature for a predeterminedtime comprises winding the wire and heat treating the wire at apredetermined temperature for a predetermined time after winding thewire.